The present invention relates to the technology to establish data communication via a communication network and, more particularly, the technology to control bandwidths assigned to the data communication.
Recently, the streaming is utilized popularly through the spread of high-speed data communication technology such as ADSL, or the like. This streaming distributes motion picture data or music data via the communication network, and the user reproduces a motion picture from the motion picture data and a music piece from the music data in real time.
In the streaming of this type, it is important that the motion picture data or the music data as the transmission object should be delivered without fail to the destination at a predetermined transmission speed, in other words, qualities of service (also referred to as “QoS” hereinafter) such as a transmission speed, a transmission delay, and the like should be maintained constant. Therefore, the technology to ensure QoS has been proposed variously in the prior art. By way of example, two types of technologies, i.e., the “traffic shaping system” and the “priority queueing system” can be given.
The traffic shaping system provides such a control system that a series of data transmitted via the communication network (also referred to as the “traffic” hereinafter) are classified in accordance with predetermined rules and then a predetermined bandwidth is assigned to every classified traffic. In contrast, the priority queueing system provides such a control system that the priority is assigned to the classified traffics respectively and then the traffic is sent out sequentially to the communication network in order of higher priority.
Also, in the technology disclosed in JP-A-2000-270023, a band used in the priority queueing system is secured separately from a band used in the traffic shaping system and then traffic transmission control (referred simply to as the “traffic control” hereinafter) is executed by combining the traffic shaping system and the priority queueing system with each other in parallel.
However, according to the technology disclosed in JP-A-2000-270023, the band used in the priority queueing system must be kept previously and thus such band cannot be used in the traffic shaping system. Therefore, such band cannot be used at all when the traffic as the control object in the priority queueing system is not present.
Also, according to the technology disclosed in JP-A-2000-270023, it is possible to apply the traffic shaping system and the priority queueing system in combination, nevertheless a way of combining both systems is limited to the parallel combination as mentioned above.